Process for the manufacture of urea-formaldehyde condensation polymers containing sulpho groups

ABSTRACT

The invention relates to the manufacture of urea-formaldehyde condensation polymers containing sulpho groups. The starting material is a urea-formaldehyde precondensate, and a condensation polymer of naphthalenesulphonic acid and formaldehyde is used as the acid catalyst for the subsequent polycondensation of the urea-formaldehyde precondensate. The peculiarity of this polycondensation is that the condensation catalyst is incorporated into the polymer structure of the UF polymer. 
     The products obtained according to the invention are distinguished by improved surface affinity coupled with interparticle porosity. They can be used as fillers, as adsorbents, as carriers and as thickeners.

Several processes for the manufacture of highly disperseurea-formaldehyde polycondensation products of large specific surfacearea have already been disclosed. In this context reference may be made,for example, to a publication by A. Renner "Kondensationspolymere ausHarnstoff und Formaldehyd mit grosser spezifischer Oberflache"("Condensation Polymers of Urea and Formaldehyde, having a largespecific surface area") in "Die makromolekulare Chemie" 149 (1971) 1-27.Further communications on the manufacture of urea-formaldehydecondensation polymers are to be found in the reference book "Methodender organischen Chemie" ("Methods of Organic Chemistry") (Houben-Weyl);Makromolekulare Stoffe (Macromolecular Substances), part 2, 320 et seq.(Page 316 of this volume also mentions the condensation of formaldehydewith sulphonated naphthalene, to give soluble products). The followingspecifications may be mentioned as relevant patents and patentapplications: U.S. Pat. No. 3,553,115; German Auslegeschrift 1,907,914,Austrian Pat. No. 315,493 and British Pat. No. 1,318,244.

In these known processes for the manufacture of ureaformaldehydepolycondensation products, the starting materials are either themonomeric components urea (U) and formaldehyde (F), or UFprecondensates. The polycondensation is carried out in aqueous solutionin the presence of acid catalysts.

Usable polymers are obtained, for example, by employing sulphamic acidor a water-soluble ammonium bisulphate as the catalyst. However, usingthe process for the manufacture of UF polycondensation productsaccording to the state of the art, highly disperse substances areobtained, which do not possess the optimum properties inherently desiredin connection with certain applications. Thus, many of these products donot adequately exhibit certain surface affinity properties which resultin particularly good bonds in rubber mixtures, or bonds to certaindyestuffs. Some of the UF polycondensation products manufactured inaccordance with these known processes can admittedly be used readily asactive fillers for rubber, but the ability of these materials to absorboil or active compounds is limited. Furthermore, the manufacture ofpellets or granules of these UF polycondensation products is ratherexpensive and difficult, since the material tends to crumble. The knownprocesses for the manufacture of such UF polymers furthermore stillrequire improvement in respect of the fact that the acid catalyst mustbe removed from the end product by laborious washing.

It is the object of the invention to provide modified urea-formaldehydepolycondensation products with improved properties. The products shouldas far as possible not exhibit the abovementioned disadvantages withrespect to surface affinity and absorbency. It is a further object ofthe invention so to design the process of manufacture of such polymersthat the laborious washing-out of the acid condensation catalyst isunnecessary.

The object of the invention has been achieved by using aurea-formaldehyde precondensate as the starting material and employing,as the acid catalyst for the polycondensation of this precondensate, acondensation polymer of naphthalenesulphonic acid and formaldehyde. Thepeculiarity of the solution of the invention is that this condensationcatalyst is incorporated into the chain molecule of the UF polymer.

Accordingly, the subject of the invention is a process for themanufacture of highly disperse, solid urea-formaldehyde condensationproducts which are modified by sulpho groups and consist of compact,spherical, agglomerated primary particles of diameter less than 1 μm,which is characterised in that a precondensate (P) of urea andformaldehyde and a condensation polymer (N) of naphthalenesulphonic acidand formaldehyde are polycondensed in aqueous solution at temperaturesof 20 to 100° C to form a gel, the components being used in such ratiothat the molar ratio of formaldehyde to urea in the reaction mixture atthe moment of gelling is 1.25 to 2, these molar ratios taking intoaccount both the free starting products (formaldehyde and urea) and themonomeric starting products chemically bound in the intermediateproducts, and that the resulting gel is optionally comminuted,suspended, optionally neutralised, filtered off and dried, and theproduct thus obtained is optionally deagglomerated by means of a mill orworked up into granules by a build-up granulation process, preferably byextrusion.

According to the process of the invention, the condensation polymer (N)should preferably be present in the reaction mixture in such amount asto provide 10 to 150 milliequivalents of the group --SO₃ H per mol ofurea. In general, particularly advantageous results are obtained with 20to 50 milliequivalents of the group --SO₃ H per mol of urea. Thisprocedure therefore represents a particularly preferred form of theinvention.

The concentration of the aqueous reaction mixture, with respect to thesum of the precondensate (P) and the condensation polymer (N), shouldpreferably be 15 to 40% by weight (based on the solution). Particularlygood polymers are obtained with a concentration of 20 to 25% by weight.

The precondensates (P) are manufactured in accordance with knownprocesses by condensation of F and U in aqueous solution. According tothe invention, precondensates (P) which contain F and U in the molarratio of 1.3 to 1.8, and precondensates which have been manufactured byprecondensation of the reactants in the pH range of 6 to 9 and in thetemperature range of 20° to 100° C, are employed.

The condensation polymer (N) should preferably contain the components insuch ratios as to provide 0.7 to 2.2 mols of formaldehyde per mol ofnaphthalenesulphonic acid. The best results are obtained if the molarratio of F to naphthalenesulphonic acid is 1.0 to 1.5.

The condensation polymer (N) is manufactured in accordance with knownprocesses by condensation of naphthalenesulphonic acid with formaldehydein aqueous solution. In general, technical naphthalenesulphonic acidwhich, as is known, predominantly contains the 2-sulphonic acid, andalso a little free sulphuric acid, is employed. The naphthalenesulphonicacid can also be manufactured in situ during the manufacture of thecondensation polymer (N).

The polycondensation according to the invention can also be carried outin such a way that comonomers partially replace urea (namely in up to1/3 of the molar amount), that is to say that such comonomers are alsoincorporated into the chain molecule. These comonomers are substanceswhich, like urea, can form polycondensates with formaldehyde or methylolcompounds. The following substances may be mentioned individually:phenol, resorcinol, alkylphenols (such as the cresols), aniline,benzoguanamine, acid amides (such as formamide, acrylamide,dicyandiamide and oxalic acid diamide), salicylic acid, biuret andhydantoins (such as, for example, 5,5-dimethylhydantoin). Mixtures ofindividual substances of this type can also be used as comonomers.

The comonomers can be incorporated in two ways. Either a precondensate(P), in which up to 1/3 of the amount of urea inherently envisaged isreplaced by a corresponding molar amount of comonomer, is employed, or aprecondensate (P) with a correspondingly lower urea content (up to 1/3lower than that inherently envisaged) is employed and the requisiteamount of the particular comonomer is added to the reaction mixture,containing the precondensate (P) and the condensation polymer (N),before or during the polycondensation.

The products manufactured by the process according to the invention showstrong hydrogen bridge bonds and are therefore not soluble in customaryorganic solvents. On the other hand, they are soluble in hot formic acidand in saturated aqueous solutions of lithium bromide and magnesiumperchlorate. They can be reprecipitated from these solutions. They meltaround 250° C, with evolution of formaldehyde.

The products manufactured according to the invention can be used asreinforcing fillers for elastomers, as adsorbents for sewagepurification, particularly for breaking spent oil emulsions, as carriersfor active compounds in agricultural chemistry, and as thickeners andsolidifying agents for lacquers, printing inks, liquid feedstuffs andthe like. They are particularly effective when used for this purpose,because of their improved surface affinity coupled with interparticleporosity.

The products obtainable by using the process according to the inventioncan be converted surprisingly advantageously into pellets or granules.The known processes for build-up granulation such as, for example,tableting, extrusion or build-up by means of a granulating disc, can beused for this purpose. In contrast to known UF polycondensates, theproducts manufactured according to the invention show astonishinglylittle tendency to crumble.

The successful solution of the object of the invention was surprising ifprevious experience with condensation catalysts containing sulpho groupsis taken into account. In fact, using the known processes for themanufacture of UF polycondensation products employing sulphamic acid orwater-soluble ammonium bisulphates as catalysts it has never provedpossible to build these catalysts into the molecule of the condensationpolymer.

A further surprising feature of the process according to the inventionis that to achieve the large surface area and good properties of the endproducts it is, in contrast to other known UF polycondensationprocesses, not necessary to add surface-active substances or protectivecolloids. Admittedly this does not mean that such addition has anadverse effect on the process according to the invention. There may becases in which an addition of such substances is desirable, for examplefor technological reasons.

A further subject of the invention are highly disperse solidurea-formaldehyde polycondensation products which are modified by sulphogroups and consist of compact, spherical, agglomerated primary particlesof diameter less than 1 μm, and which are manufactured in accordancewith the process of the invention. The UF polycondensation productsaccording to the invention preferably have a specific surface area of 5to 100 m² /g, a sulphur content of 0.2 to 2% by weight and an averagediameter of the primary particles of 0.04 to 1 μm. The UFpolycondensation products according to the invention can contain acomonomer as a partial replacement for urea, the molar ratio ofcomonomer to urea being up to 1/2.

In the examples which follow, parts denote parts by weight andpercentages denote percentages by weight.

EXAMPLES A) Manufacture of the condensation polymers (N)

a. Condensation polymer (N) - A

Naphthalene : H₂ SO₄ : formaldehyde = 1:1:1 (molar ratio)

128 parts of naphthalene and 100 parts of concentrated sulphuric acidare heated for 6 hours to 160° C, whilst stirring. The mixture is cooledto 100° C and 100 parts of an aqueous 30% strength formaldehyde solutionare added dropwise. The temperature is kept at 100° C by the heat ofreaction which is liberated. After boiling for 30 minutes under reflux,the mixture is diluted with 100 parts of water. After a further 16hours' boiling under reflux, a formaldehyde conversion of 94.5% isreached. The mixture is diluted with a further 100 parts of water and510 parts of a brown, viscous solution having a solids content of 45.5%and an acid content of 2.17 equivalents/kg are obtained. The acid resinsolution can be diluted with water in any desired ratio.

b. Condensation polymer (N) - B

Naphthalene : H₂ SO₄ : formaldehyde = 1:1:1.5

128 parts of naphthalene are sulphonated with 100 parts of concentratedsulphuric acid for 6 hours at 160° C and then condensed with 150 partsof aqueous 30% strength formaldehyde solution at 100°-110° C. Themixture was diluted, and the conversion determined, after the timesshown.

    ______________________________________                                        Hours at Addition of parts of                                                                          CH.sub.2 O conversion                                100-110° C                                                                      H.sub.2 O       (%)                                                  ______________________________________                                        12.5     40              --                                                   17.0     --              79.6                                                 19.5     60              --                                                   23.5     --              81.7                                                 24.0     100             --                                                   40.0     --              85                                                   48.0     --              85.2                                                 ______________________________________                                    

After cooling, 512 parts of a viscous brown resin are obtained, which ismiscible with water in any desired ratio and gives colloidal solutions.The resin has a solids content of 44.5% and an acid content of 2.12equivalents/kg.

c. Condensation polymer (N) - C

C₁₀ H₈ : H₂ SO₄ : CH₂ O = 1:1:2

Following the procedure described in the preceding examples, 128 partsof naphthalene are sulphonated with 100 parts of concentrated sulphuricacid and then condensed with 200 parts of 30% strength aqueousformaldehyde solution for 22 hours at 100° C and diluted with 100 partsof water. Thereafter, the conversion of the formaldehyde is 76.6%. 472parts of a resin which is almost solid but is miscible with water in anydesired ratio and gives colloidal solutions, are obtained. The solidscontent is 50% and the acid content is 2.09 equivalents/kg.

d. Condensation polymer (N) - D

C₁₀ H₈ : H₂ SO₄ : CH₂ O = 1:1:0.75

128 parts of naphthalene are sulphonated with 100 parts of concentratedsulphuric acid for 6 hours at 160° C and then condensed with 75 parts of30% strength aqueous formaldehyde solution for 29 hours at 110° - 120°C. Towards the end of this reaction time, the mixture was diluted twicewith 100 parts of water.

    ______________________________________                                        Yield              475 parts                                                  Solids content     45%                                                        Acid content       2.2 equivalents/kg                                         Dilutability with H.sub.2 O                                                                      ∞                                                    ______________________________________                                    

e. Condensation polymer (N) - E

C₁₀ H₈ : H₂ SO₄ : CH₂ O = 1:1.4:1.1

128 parts of naphthalene are sulphonated with 110 parts of concentratedsulphuric acid for 6 hours at 160° C and condensed with 110 parts of 30%strength aqueous formaldehyde solution at 100° - 110° C. After thereaction times shown, the mixture was diluted as shown and theformaldehyde conversions shown were determined:

    ______________________________________                                        Hours at Addition of parts of                                                                          CH.sub.2 O conversion                                100-110° C                                                                      H.sub.2 O       (%)                                                  ______________________________________                                        3        100             --                                                   26.5     --              81.8                                                 30       100             --                                                   45       --              87.5                                                 72       --              90.9                                                 78        50             90.9                                                 Yield             570 parts                                                   Solids content    43%                                                         Acid content      2.16 equivalents/kg                                         Dilutability with H.sub.2 O: ∞                                          ______________________________________                                        f. Condensation polymer (N) - F

Naphthalenesulphonic acid : CH₂ O = 1 (molar ratio).

343.8 parts of technical naphthalenesulphonic acid (predominantly the2-acid, 5.82 equivalents of --SO₃ H/kg) and 200 parts of 30% strengthaqueous formaldehyde solution are condensed at 100° C.

    ______________________________________                                        Hours at addition of parts of                                                                          CH.sub.2 O conversion                                100-102° C                                                                      H.sub.2 O       (%)                                                  ______________________________________                                        5        100             --                                                   21.5     56              --                                                   22.0     --              76.3                                                 23.0     34              --                                                   41.0     100             --                                                   46.0     --              78.3                                                 53.0     --              79.8                                                 68.0     10              80.0                                                 Yield             877 parts                                                   Solids content    42.5%                                                       Acid content      2.255 equivalents/kg                                        Dilutability with H.sub.2 O                                                                     ∞                                                     ______________________________________                                    

g. Condensation polymer (N) - G

Naphthalenesulphonic acid : CH₂ O = 1.5 (molar ratio).

343.8 parts of technical naphthalenesulphonic acid (predominantly the2-acid, 5.82 equivalents of --SO₃ H/kg) and 300 parts of 30% strengthaqueous formaldehyde solution are condensed at 100° C.

    ______________________________________                                        Hours at Addition of parts of                                                                          CH.sub.2 O conversion                                100° C                                                                          H.sub.2 O       (%)                                                  ______________________________________                                        4.5      100             --                                                   21.5     --              55.8                                                 42.0     --              66.7                                                 64.0     10              74.4                                                 Yield             686 parts                                                   Solids content    57.2%                                                       Acid content      3.00 equivalents/kg                                         Dilutability with H.sub.2 O                                                                     ∞                                                     ______________________________________                                    

B) MANUFACTURE OF THE UREA-FORMALDEHYDE POLYCONDENSATION PRODUCTSEXAMPLES 1 - 3

900 parts of urea are dissolved in 2,100 parts of water, the solution iswarmed to 70° C, 2,250 parts of 30% strength aqueous formaldehydesolution are added, condensation is carried out for 30 minutes at pH 7and 70° C, and the mixture is cooled to 50° C. This precondensate isdivided into 3 equal parts which are mixed with solutions of thecondensation polymer (N)-B at 50° C, and converted into polymer gels, inaccordance with the conditions indicated below.

    __________________________________________________________________________    Example No.         1     2     3                                             __________________________________________________________________________    Parts of condensation polymer (N)-B                                                               47.2  53.1  59.1                                          dissolved in parts of H.sub.2 O                                                                   303   530   815                                           gelling concentration (% by weight                                            of U + F)           25    22.5  20                                            milliequivalents of SO.sub.3 H/mol of urea                                                        20    22.5  25                                            gelling time (sec.) 25    27    29                                            gelling pH          2.1   2.1   2.1                                           temperature rise to ° C:                                                                   65    64    63                                            __________________________________________________________________________

Each gel is kept at 65° C for 2 hours, comminuted, stirred thoroughlywith 2,000 parts of water and adjusted to pH 7.5 with 2 N NaOH. Thepolymers are filtered off, dried overnight in a stream of air at 110° Cand deagglomerated by passing them through an air jet mill with an inputpressure of 40 atmospheres. Very bulky white polymer powders areobtained.

    __________________________________________________________________________    Example No.       1     2     3                                               __________________________________________________________________________    Yield (parts)     400   404   401                                             specific surface area (m.sup.2 /g)                                                              67.8  80.8  78.8                                            average diameter of the primary                                               particles (A)     600   510   520                                             agglomerates (μm)                                                                            3.7   3.8   4.4                                             residual moisture (%)                                                                           5.6   5.8   5.4                                             bulk density (g/l)                                                                              124   100   125                                             oil absorbency (% DBP)                                                                          200   228   174                                             sulphur content (%)                                                                             0.4   0.7   0.9                                             __________________________________________________________________________     (The oil absorbency was determined by the method of Wolff and Toeldte).  

EXAMPLES 4 - 6

The same precondensate as in Examples 1 - 3 is prepared and divided into3 equal parts; these are mixed, at 50° C, with the amounts of thecondensation polymer (N)-A indicated below, and the mixtures areconverted into polymer gels.

    __________________________________________________________________________    Example No.         4     5     6                                             __________________________________________________________________________    parts of condensation polymer (N)-A                                                               46.2  52.0  58.0                                          dissolved in parts of H.sub.2 O                                                                   300   530   820                                           gelling concentration (% by weight                                            of U + F)           25    22.5  20                                            milliequivalents of SO.sub.3 H/mol of urea                                                        20    22.5  25                                            gelling time (sec.) 20    22    25                                            gelling pH          2.0   2.0   2.0                                           __________________________________________________________________________

After comminution, each gel is stirred with 2,500 parts of water but isotherwise treated like the gels in Examples 1 - 3.

    __________________________________________________________________________    Example No.       4     5     6                                               __________________________________________________________________________    Yield (parts)     393   393   396                                             specific surface area (m.sup.2 /g)                                                              58.1  85.6  62.5                                            average diameter of the primary                                               particles (A)     660   480   660                                             agglomerates (μm)                                                                            3.8   3.4   3.0                                             residual moisture (%)                                                                           3.5   3.6   3.6                                             bulk density (g/l)                                                                              39.6  33.0  24.0                                            oil absorbency (% DBP)                                                                          371   391   424                                             sulphur content (%)                                                                             0.7   0.7   0.85                                            __________________________________________________________________________    ______________________________________                                        Example 7                                                                     ______________________________________                                        Precondensate:                                                                Urea                   180 parts                                              formaldehyde (30%)     450 parts                                              deionised water        300 parts                                               30 minutes at pH 7.0 and 70° C                                        condensation polymer (N)-C                                                                           28.7 parts                                             dissolved in H.sub.2 O 300 parts                                              gelling concentration (%)                                                                            25                                                     milliequivalents of SO.sub.3 H/mol of urea                                                           20                                                     gelling time (sec.)    18                                                     temperature variation (° C)                                                                   gelling pH 2.1                                         parts of H.sub.2 O used to work up the gel                                                           1500                                                   further working up as in Examples                                                                    1 - 3                                                  yield (parts)          237                                                    specific surface area (m.sup.2 /g)                                                                   70                                                     average diameter of the primary                                               particles (A)          590                                                    average diameter of the agglomerates                                          (μm)                4.3                                                    residual moisture (%)  2.1                                                    bulk density (g/l)     130                                                    oil absorbency (% DBP) 227                                                    sulphur content (%)    0.7                                                    ______________________________________                                        ______________________________________                                        Example 8                                                                     ______________________________________                                        Urea (parts)           300                                                    deionised water        700                                                    formaldehyde, 30% strength                                                                           750                                                     30 minutes at pH 7 and 70° C                                          parts of condensation polymer (N)-E                                                                  57.9                                                   dissolved in parts of H.sub.2 O                                                                      816                                                    gelling concentration (% U+F)                                                                        20                                                     milliequivalents of SO.sub.3 H/mol of urea                                                           25                                                     gelling time (sec.)    25                                                     gelling pH                                                                    temperature variation, ° C                                                                    parts of H.sub.2 O used to work up the gel 2500        at pH                  7.5                                                    drying and working up as in examples                                                                 1 - 3                                                  yield (parts)          397                                                    specific surface area (m.sup.2 /g)                                                                   63.7                                                   average diameter of primary particles (A)                                                            650                                                    average diameter of agglomerates (μm)                                                             3.5                                                    residual moisture (%)  3.5                                                    bulk density (g/l)     37                                                     oil absorbency (% DBP) 339                                                    sulphur content (%)    0.75                                                   ______________________________________                                    

EXAMPLES 9 to 20

Table I shows further examples in which the condensation polymers (N),type F (Examples 9 - 14) and type G (Examples 15 - 20) are employed.Both series of experiments show that the properties of thepolycondensates which can be prepared in this way are dependent on themolar ratio of formaldehyde/urea.

EXAMPLES 21 to 31

These examples are shown in Table II. The condensation polymer (N), typeG, is employed in various concentrations. The gelling concentration andthe catalyst concentration are also varied.

EXAMPLES 32 to 44

These examples are shown in Table III and relate to the manufacture ofthe urea-formaldehyde polycondensation products according to theinvention in the presence of various comonomers. According to Examples39 to 44, the particular comonomer is essentially built into themolecule already during the manufacture of the precondensate (P), thatis to say the total amount of comonomer is already present in thereaction mixture during the precondensation (P).

According to Examples 32 to 38, in contrast to the above method, thecomonomer is only added to the reaction mixture for the finalpolycondensation after the manufacture of the precondensate (P) and ofthe condensation polymer (N). Here, therefore, the comonomer is onlybuilt into the polycondensate in the final stage.

                                      Table I                                     __________________________________________________________________________    Example No.   9   10  11  12  13  14                                          __________________________________________________________________________    parts of urea 300 300 300 300 300 300                                         parts of H.sub.2 O                                                                          600 600 600 600 600 600                                         parts of 30% strength                                                         formaldehyde  650 700 750 800 850 900                                         CH.sub.2 O/urea                                                                             1.3 1.4 1.5 1.6 1.7 1.8                                         precondensation                                                                             30 minutes at pH 7 and 70° C                             condensation polymer                                                          (N) - type    F   F   F   F   F   F                                           parts         55.3                                                                              55.3                                                                              55.3                                                                              55.3                                                                              55.3                                                                              55.3                                        dissolved in parts                                                            of H.sub.2 O  870 895 920 945 970 995                                         gelling concen-                                                               tration (% by weight)                                                                       20.0                                                                              20.0                                                                              20.0                                                                              20.0                                                                              20.0                                                                              20.0                                        milliequivalents of                                                           condensation polymer                                                          (N) per mol of urea                                                                         25.0                                                                              25.0                                                                              25.0                                                                              25.0                                                                              25.0                                                                              25.0                                        gelling time (sec.)                                                                         22  20  24  29  31  44                                          gelling pH                                                                    temperature rise from                                                         50 to ° C                                                                            62  63  62  62  59  57                                          working up of the poly-                                                       mer as in     Examples 1 - 3                                                  yield (parts) 370 382 360 399 403 393                                         specific surface area                                                         (m.sup.2 /g)  39.7                                                                              59.3                                                                              64.7                                                                              77.9                                                                              78.8                                                                              44.9                                        d of the primary                                                              particles (A) 1040                                                                              720 660 530 525 920                                         d of the agglomerates                                                         (μm)       3.4 4.9 3.7 4.7 5.3 4.4                                         residual moisture (%)                                                                       3.6 3.5 4.0 3.8 4.2 3.8                                         bulk density (g/l)                                                                          80  50  50  78  150 250                                         oil absorbency (% DBP)                                                                      202 309 292 234 195 101                                         sulphur content (%)                                                                         0.75                                                                              0.95                                                                              0.8 0.75                                                                              0.7 0.75                                        methylol group                                                                content (%)   0.06                                                                              0.57                                                                              0.86                                                                              2.06                                                                              2.29                                                                              2.98                                        Example No.   15  16  17  18  19  20                                          __________________________________________________________________________    parts of urea 300 300 300 300 300 300                                         parts of H.sub.2 O                                                                          600 600 600 600 600 600                                         parts of 30% strength                                                         formaldehyde  650 700 750 800 850 900                                         CH.sub.2 O/urea                                                                             1.3 1.4 1.5 1.6 1.7 1.8                                         precondensation                                                                             30 minutes at pH 7 and 70° C                             condensation polymer                                                          (N) - type    G   G   G   G   G   G                                           parts         37.5                                                                              37.5                                                                              37.5                                                                              37.5                                                                              37.5                                                                              37.5                                        dissolved in parts                                                            of H.sub.2 O  612.5                                                                             627.5                                                                             645.5                                                                             662.5                                                                             677.5                                                                             694.5                                       gelling concen-                                                               tration (% by weight)                                                                       22.5                                                                              22.5                                                                              22.5                                                                              22.5                                                                              22.5                                                                              22.5                                        milliequivalents of                                                           condensation polymer                                                          (N) per mol of urea                                                                         22.5                                                                              22.5                                                                              22.5                                                                              22.5                                                                              22.5                                                                              22.5                                        gelling time (sec.)                                                                         19  20  22  23  28  37.5                                        gelling pH                                                                    temperature rise from                                                         50 to ° C                                                                            64  60  65  64  60  60                                          working up of the poly-                                                       mer as in     Examples 1 - 3                                                  yield (parts) 369 391 390 388 402 391                                         specific surface area                                                         (m.sup.2 /g)  36.0                                                                              49.5                                                                              64.3                                                                              76.4                                                                              85.9                                                                              44.9                                        d of the primary                                                              particles (A) 1180                                                                              830 640 540 480 920                                         d of the agglomerates                                                         (μm)       3.5 4.3 4.9 4.7 3.9 6.6                                         residual moisture (%)                                                                       4.1 3.1 3.3 4.6 5.3 3.1                                         bulk density (g/l)                                                                          42  39  44  60  73  250                                         oil absorbency (% DBP)                                                                      338 418 405 330 278 103                                         sulphur content (%)                                                                         0.95                                                                              0.75                                                                              0.80                                                                              0.70                                                                              0.70                                                                              0.70                                        methylol group                                                                content (%)   0.06                                                                              0.09                                                                              1.36                                                                              2.06                                                                              1.72                                                                              3.15                                        __________________________________________________________________________

                                      Table II                                    __________________________________________________________________________    Various gelling concentrations and amounts of catalyst at                     F/U = 1.7                                                                     Example No.    21  22  23  24  25                                             __________________________________________________________________________    parts of urea  180 180 180 180 180                                            parts of H.sub.2 O                                                                           500 500 500 500 150                                            parts of 30% strength                                                         formaldehyde   510 510 510 510 510                                            precondensation                                                                              30 minutes at pH 7 and 70° C                            parts of condensation                                                         polymer (N)-G  33.3                                                                              29.0                                                                              25.0                                                                              22.5                                                                              20.0                                           dissolved in parts of                                                         H.sub.2 O (% by weight)                                                                      998 685 450 270 472                                            gelling concen-                                                               tration (% by weight)                                                                        15.0                                                                              17.5                                                                              20.0                                                                              22.5                                                                              25.0                                           milliequivalents of                                                           condensation polymer                                                          (N) per mol of urea                                                                          33.3                                                                              28.6                                                                              25.0                                                                              22.5                                                                              20.0                                           gelling time (sec.)                                                                          50.0                                                                              44  38  36  33                                             temperature rise from                                                         50 to ° C                                                                             58  58  61  61  63                                             yield (parts)  223 224 230 230 238                                            specific surface area                                                         (m.sup.2 /g)   53.9                                                                              68.9                                                                              78.6                                                                              76.6                                                                              74.8                                           residual moisture (%)                                                                        4.2 4.8 4.3 4.3 3.5                                            bulk density (g/l)                                                                           280 230 133 122 90                                             oil absorbency (% DBP)                                                                       99  121 203 233 319                                            methylol group content                                                        (%)            2.52                                                                              --  2.36                                                                              --  2.04                                           Example No.    26  27  28  29  30  31                                         __________________________________________________________________________    parts of urea  180 180 180 180 180 180                                        parts of H.sub.2 O                                                                           150 150 150 --  --  --                                         parts of 30% strength                                                         formaldehyde   510 510 510 510 510 510                                        precondensation                                                                              30 minutes at pH 7 and 70° C                            parts of condensation                                                         polymer (N)-G  18.5                                                                              17.0                                                                              15.5                                                                              14.3                                                                              13.4                                                                              12.5                                       dissolved in parts of                                                         H.sub.2 O (% by weight)                                                                      355 260 170 248 185 130                                        gelling concen-                                                               tration (% by weight)                                                                        27.5                                                                              30.0                                                                              32.5                                                                              35  37.5                                                                              40.0                                       milliequivalents of                                                           condensation polymer                                                          (N) per mol of urea                                                                          18.2                                                                              16.7                                                                              15.4                                                                              14.3                                                                              13.3                                                                              12.5                                       gelling time (sec.)                                                                          28  25  26  23  21  19                                         temperature rise from                                                         50 to ° C                                                                             65  66  67  67  69  70                                         yield (parts)  240 242 237 216 228 235                                        specific surface area                                                         (m.sup.2 /g)   70.4                                                                              69.4                                                                              66.2                                                                              64.4                                                                              65.2                                                                              62.7                                       residual moisture (%)                                                                        5.8 5.1 4.7 3.1 3.3 3.1                                        bulk density (g/l)                                                                           80  89  88  101 94  105                                        oil absorbency (% DBP)                                                                       379 399 409 336 350 353                                        methylol group content                                                        (%)            --  2.61                                                                              2.30                                                                              3.09                                                                              3.32                                                                              3.25                                       __________________________________________________________________________

                                      Table III                                   __________________________________________________________________________    Additional use of condensation comonomers                                     Example No.   32    33    34    35                                            __________________________________________________________________________    parts of urea 162   135   162   135                                           parts of H.sub.2 O                                                                          421   450   412   486                                           parts of 30% strength                                                         formaldehyde  510   510   510   510                                           comonomer, a) type                                                                          phenol                                                                              phenol                                                                              m-cresol                                                                            m-cresol                                       b) parts     28.2  70.5  32.4  81                                             c) present during                                                                          FPC*  FPC   FPC   FPC                                           precondensation minutes                                                       at pH 7 and 70° C                                                                    30    30    30    30                                            parts of condensation                                                         polymer (N)-G 22.5  22.5  22.5  22.5                                          parts of H.sub.2 O                                                                          405   405   405   405                                           gelling concentration                                                         ***(% by weight)                                                                            22.5  22.5  22.5  22.5                                          milliequivalents of                                                           condensation polymer                                                          (N) per mol of urea/                                                          comonomer     22.5  22.5  22.5  22.5                                          gelling time (sec.)                                                                         31    47    18    90                                            gelling pH    1.7   1.5   1.8   1.5                                           temperature rise from                                                         50° C to                                                                             60    58    61    62                                            yield (parts) 251   260   254   259                                           specific surface area                                                         (m.sup.2 /g)  67.9  45.8  35.7  29.3                                          residual moisture (%)                                                                       3.6   2.6   3.6   3.6                                           bulk density (g/l)                                                                          86    53    49    86                                            Oil absorbency (% DBP)                                                                      446   313   496   294                                           Example No.   36    37    38    39                                            __________________________________________________________________________    parts of urea 162   135   162   180                                           parts of H.sub.2 O                                                                          414   510   443   408                                           parts of 30% strength                                                         formaldehyde  510   510   510   510                                           comonomer, a) type                                                                          resorcinol                                                                          resorcinol                                                                          salicylic                                                                           formamide                                                               acid                                                 b) parts     33    82.5  41.4  13.5                                           c) present during                                                                          FPC*  FPC   FPC   UF-PC**                                       precondensation,                                                              minutes at pH 7 and                                                           70° C  30    30    30    120                                           parts of condensation                                                         polymer (N)-G 22.5  22.5  22.5  24.8                                          parts of H.sub.2 O                                                                          405   405   405   405                                           gelling concentration                                                         *** (% by weight)                                                                           22.5  22.5  22.5  22.5                                          milliequivalents of                                                           condensation polymer                                                          (N) per mol of urea/                                                          comonomer     22.5  22.5  22.5  22.5                                          gelling time (sec.)                                                                         7     5     32    31                                            gelling pH    1.8   1.5   1.5   1.5                                           temperature rise from                                                         50° C to                                                                             65    71    58    61                                            yield (parts) 248   277   237   239                                           specific surface area                                                         (m.sup.2 /g)  58.1  26.2  50.3  73.6                                          residual moisture (%)                                                                       2.0   3.2   3.1   2.6                                           bulk density (g/l)                                                                          51    44    197   176                                           oil absorbency (% DBP)                                                                      520   551   158   168                                           Example No.   40    41    42    43    44                                      __________________________________________________________________________    parts of urea 180   135   300   135   162                                     parts of H.sub.2 O                                                                          474   434   600   472   433                                     parts of 30% strength                                                         formaldehyde  510   510   700   510   510                                     comonomer, a) type                                                                          form- oxalic                                                                              acryl-                                                                              biuret                                                                              5,5-                                                  amide acid  amide       dimethyl-                                                   diamide           hydantoin                                b) parts     33.8  66    35.5  77.3  38.4                                     c) present during                                                                          UF-PC**                                                                             UF-PC UF-PC UF-PC UF-PC                                   precondensation,                                                              minutes at pH 7 and                                                           70° C  120   120   120   120   120                                     parts of condensation                                                         polymer (N)-G 28.1  22.5  41    22.5  22.5                                    parts of H.sub.2 O                                                                          405   405   625   405   405                                     gelling concen-                                                               tration*** (% by                                                              weight)       22.5  22.5  22.5  22.5  22.5                                    milliequivalents of                                                           condensation polymer                                                          (N) per mol of urea/                                                          comonomer     22.5  22.5  22.5  22.5  22.5                                    gelling time (sec.)                                                                         37    32    26    102   53                                      gelling pH    1.6   --    1.5   --    --                                      temperature rise from                                                         50° C to                                                                             61    55    60    58    58                                      yield (parts) 247   244         250   227                                     specific surface                                                              area (m.sup.2 /g)                                                                           56.2  49.4  47.4  44.9  70.6                                    residual moisture                                                             (%)           3.7   3.2   1.8   2.1   3.5                                     bulk density (g/l)                                                                          203   215         320   207                                     oil absorbency                                                                (% DBP)       137.5 149         102   131.2                                   __________________________________________________________________________     *FPC = final polycondensation                                                 ** UF-PC = urea-formaldehyde precondensation                                  *** urea/formaldehyde/comonomer                                          

I claim:
 1. In a process for the manufacture of urea-formaldehydecondensation products the improvement according to which highlydisperse, solid urea-formaldehyde condensation products are formed whichcontain sulpho groups and consist of compact, spherical, agglomeratedprimary particles having a diameter of less than 1 μm, the processcomprising polycondensing a precondensate (P) of urea and formaldehydeand a condensation polymer (N) of naphthalenesulphonic acid andformaldehyde in aqueous solution at temperatures of 20° to 100° C toform a gel, the components being added in such ratio that the molarratio of formaldehyde to urea in the reaction mixture at the moment ofgelling is 1.25 to 2, these molar ratios taking into account both thefree starting products (formaldehyde and urea) and the monomericstarting products chemically bound in the intermediate products.
 2. Aprocess according to claim 1, wherein the polycondensation to give thecross-linked gel is carried out in such a way that 10 to 150milliequivalents of the condensation polymer (N) are present in thereaction mixture per mol of urea.
 3. A process according to claim 2,wherein the polycondensation is carried out in such a way that 20 to 50milliequivalents of the condensation polymer (N) are present whichcontains the precondensate (P) are present per mol of urea.
 4. A processaccording to claim 1, wherein the precondensate (P) employed has a molarratio of formaldehyde to urea of 1.3 to 1.8.
 5. A process according toclaim 1, wherein the condensation polymer (N) employed has a molar ratioof formaldehyde to naphthalenesulphonic acid of 0.7 to 2.2.
 6. A processaccording to claim 5, wherein the condensation polymer (N) employed hasa molar ratio of formaldehyde to naphthalenesulphonic acid of 1.0 to1.5.
 7. A process according to claim 1, wherein an aqueous solution of aprecondensate (P) which has been prepared by precondensation of thereactants in the pH range of 6 to 9 and in the temperature range of 20°to 100° C is used.
 8. A process according to claim 1, wherein thepolycondensation is carried out in an aqueous solution which containsthe precondensate (P) and the condensation polymer (N) together in aconcentration of 15 to 40% by weight based on the solution.
 9. A processaccording to claim 8, wherein the concentration is from 20 to 25% byweight.
 10. Highly disperse solid urea-formaldehyde condensationpolymers which contain sulpho groups, consist of compact, spherical,agglomerated primary particles of diameter less than 1 μm, and aremanufactured in accordance with the process of claim
 1. 11. Pulverulenturea-formaldehyde condensation polymers according to claim 10, whereinthe products have a specific surface area of 5 to 100 m² /g, a sulphurcontent of 0.2 to 2.0% by weight and an average diameter of the primaryparticles of 0.04 to 1 μm.